René's URL Explorer Experiment

{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"Remove older emit support over time","articleBody":"# Suggestion\r\n\r\n## 🔍 Search Terms\r\n\r\nremove emit target es3 es5\r\n\r\n## ✅ Viability Checklist\r\n\r\n\r\nMy suggestion meets these guidelines:\r\n\r\n* [x] This wouldn't be a breaking change in existing TypeScript/JavaScript code\r\n* [x] This wouldn't change the runtime behavior of existing JavaScript code\r\n* [x] This could be implemented without emitting different JS based on the types of the expressions\r\n* [x] This isn't a runtime feature (e.g. library functionality, non-ECMAScript syntax with JavaScript output, new syntax sugar for JS, etc.)\r\n* [x] This feature would agree with the rest of [TypeScript's Design Goals](https://github.com/Microsoft/TypeScript/wiki/TypeScript-Design-Goals).\r\n\r\n## ⭐ Suggestion\r\n\r\nFollowing #47572, once the default target has been raised to a new value, can TypeScript _remove_ emit support for the no-longer-default old version in either that same major version or the next one?\r\n\r\nUsing the example schedule in that issue:\r\n\r\n* Remove es3 emit support for 5.0, making es5 the lowest supported emit target\r\n* Remove es5 emit support for 6.0, making es2015 the lowest supported emit target\r\n* _...and so on_\r\n\r\n## 📃 Motivating Example\r\n\r\nSupporting emit to low emit targets such as ES3/5 worsens:\r\n* Dev cost for some TypeScript features: e.g. #29374's changes were mostly in emit\r\n* Output package size: e.g. `src/compiler/transformers/es2015.ts` has \u003e4k lines today (about 10% the size of `src/compiler/checker.ts`)\r\n\r\n## 💻 Use Cases\r\n\r\nIt'd be nice to have a leaner TypeScript without the cost of supporting emit for syntax compatibility the vast majority of runtimes no longer need.\r\n","author":{"url":"https://github.com/JoshuaKGoldberg","@type":"Person","name":"JoshuaKGoldberg"},"datePublished":"2022-01-24T01:59:34.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":1},"url":"https://github.com/47573/TypeScript/issues/47573"}